The present invention generally relates to batteries and, more particularly, to removing hydrogen released from batteries, and is particularly useful for batteries used in sealed compartments such as in a packaged camera, a sealed flashlight, or other sealed device.
Conventional alkaline electrochemical cells generally include a steel cylindrical can having a positive electrode, referred to as the cathode, which comprises manganese dioxide as the active material, and is generally formed against the interior surface of the steel can. The electrochemical cell also includes a negative electrode, referred to as the anode, which comprises zinc powder, and is generally centrally disposed in the can. A separator is located between the anode and the cathode, and an alkaline electrolyte solution simultaneously contacts the anode, the cathode, and separator. A conductive current collector is commonly inserted into the anode active material and a seal assembly, which includes a seal member, provides closure to the open end of the cell""s steel can to seal the active electrochemical materials in a sealed volume.
Standard alkaline cells are commercially available for providing an open circuit voltage of about 1.5 volts. When a higher voltage is required, it is common practice to combine multiple cells to form a battery having the required voltage. In doing so, a plurality of cells are commonly housed in a container and are electrically connected in series. Additionally, external terminals are attached to the outside of the container for making an electrical connection with the cells.
It is generally known that small amounts of hydrogen are produced inside an alkaline cell due to corrosion of the zinc anode. Typically, a portion of the hydrogen accumulates inside the sealed volume of the battery, while some of the hydrogen permeates through and around the seal, and therefore escapes from the cell""s closed volume. Additionally, ventable seals are often used which open and release hydrogen when excessive pressure builds up in the closed volume. Excessive accumulation of hydrogen can present potentially unacceptable conditions, particularly in sealed compartments. For example, hydrogen may become concentrated in the sealed battery compartment of a flashlight or other electrically-operated device, and can potentially lead to problems in operating the device. As another example, the concentration of hydrogen in a disposable camera that is commercially made available in a sealed airtight package may adversely reduce silver in the photographic film and fog the film, thereby degrading the camera""s photographic film.
Hydrogen getters and recombination catalysts have been available to remove hydrogen. For example, it has been known that hydrogen absorbing materials, such as hydrogen getters, and recombination catalysts, can be used to counteract hydrogen accumulation, by disposing the hydrogen removing material in the sealed battery compartment of a device such as a flashlight. However, only certain selected electrically-operated devices are made available with a hydrogen removing material. In addition, damage or breakdown of the hydrogen removing agent over time may reduce its effectiveness in the device.
Accordingly, it is desirable to reduce the hydrogen accumulation that may be present in or around a battery. In addition, it is desirable to provide for removal of an accumulation of hydrogen gas from a battery for use in sealed battery-operated devices. Further, it is desirable to remove hydrogen emitted from batteries in a flashlight, a camera, or other similar devices.
The present invention provides for the removal of hydrogen generated by a battery by providing the battery with a hydrogen removing agent. A battery is provided having walls defining a volume and including an active cell volume for housing active cell materials. Electrochemically active materials are contained in the active cell volume of the container. The battery further includes a hydrogen removing agent disposed on the battery external from the active cell volume of the container for removing hydrogen produced by the electrochemically active materials. According to one embodiment, the hydrogen removing agent is disposed on the surface of a seal member that is disposed within an open top end of the container. According to another embodiment, the hydrogen removing agent is disposed on an inner surface of an outer cover of the battery. According to yet another embodiment, the hydrogen removing agent is disposed on a label on the outside walls of the container. According to a further embodiment, the hydrogen removing agent is disposed on the interior walls of a multi-cell battery.
These and other features, advantages and objects of the present invention will be further understood and appreciated by those skilled in the art by reference to the following specification, claims and appended drawings.